Those outer seals have more friction than the inner seals which is why most race-only forks do away with them.I didn't notice that before. I'm assuming you ditch it in an effort to minimize stiction?
The entire Ohlins FGR lineup is missing dust seals. You can't even install one if you wanted to because the retaining ring is right up against the lip of the fork lower. Have changed oil a couple times and can confirm that the oil is very dark.
It's true that it will need more frequent servicing but Ohlins has a clever compromise in their FGR's to have 2 separate oil compartments one for the piston/valves and other for the seal/fork tubes. That way the crud cannot interfere with the damping characteristics.